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More on the Jeholopterus pycnofiber study



David Hone's review:
http://archosaurmusings.wordpress.com/2009/08/05/what-on-earth-are-pycnofibe
rs/

The paper itself:
http://rspb.royalsocietypublishing.org/content/early/2009/07/31/rspb.2009.08
46.full
Alexander W. A. Kellner, Xiaolin Wang, Helmut Tischlinger, Diogenes de
Almeida Campos, David W. E. Hone, and Xi Meng

The soft tissue of Jeholopterus (Pterosauria, Anurognathidae,
Batrachognathinae) and the structure of the pterosaur wing membrane. 2009.
Proc. R. Soc. B published online before print August 5, 2009,
doi:10.1098/rspb.2009.0846

Abstract

The soft tissue preserved in the holotype (IVPP V12705) of Jeholopterus
ningchengensis from the Daohugou Bed (Late Jurassic or Early Cretaceous) of
China is described in detail. The plagiopatagium can be divided into the
distal, comparatively more rigid actinopagatium and a proximal, more tensile
tenopatagium. The actinopatagium extends from the wing finger to the
articulation between the humerus and the forearm, and shows the presence of
at least three layers containing actinofibrils. In each layer, the
actinofibrils are parallel to subparallel, but this direction diverges from
layer to layer. When distinct layers of actinofibrils are superimposed
(owing to taphonomic compression), a reticular pattern is generated. The
presence of layers with differently oriented actinofibrils is widespread in
this pterosaur. A well-developed integumental covering formed by fibres
(here named pycnofibres) that are thicker than the actinofibrils is present.
Ungual sheaths that extend the length of the pedal and manual claws of this
taxon are also observed. Although the understanding of the mechanical
properties of the wing membrane is hampered by the lack of knowledge
regarding the composition of the actinofibrils, the configuration observed
in Jeholopterus might have allowed subtle changes in the membrane tension
during flight, resulting in more control of flight movements and the
organization of the wing membrane when the animal was at rest. 



Thomas R. Holtz, Jr.
Email: tholtz@umd.edu   Phone: 301-405-4084
Office: Centreville 1216                        
Senior Lecturer, Vertebrate Paleontology
Dept. of Geology, University of Maryland
http://www.geol.umd.edu/~tholtz/
Fax: 301-314-9661               

Faculty Director, Earth, Life & Time Program, College Park Scholars
http://www.geol.umd.edu/~jmerck/eltsite/
Faculty Director, Science & Global Change Program, College Park Scholars
http://www.geol.umd.edu/sgc
Fax: 301-314-9843

Mailing Address:        Thomas R. Holtz, Jr.
                        Department of Geology
                        Building 237, Room 1117
                        University of Maryland
                        College Park, MD 20742 USA